Synthetic lubricants resistant to shear and cold

ABSTRACT

Shear-resistant and cold-resistant synthetic lubricants consisting of a mixture of esters of branched-chain dicarboxylic acids of from 16 to 22 carbon atoms and aliphatic alcohols of less than 6 carbon atoms with polymers of butenes having a molecular weight of from 1,200 to 4,500, the ester portion being from 10 to 95% by weight and the polymer portion from 90 to 5% by weight.

United States Patent 1 Fischer et al.

[451 Jan. 14,1975

SYNTHETIC LUBRICANTS RESISTANT TO SHEAR AND COLD Inventors: Diether Fischer, 7 1m Sandgarter,

Wachenheim; Paul Hornberger, 12 In den Zlegelgaerten; Willy Wolf, 8 Alwin-Mit1asch-Platz,, both of Ludwigshafen, all of Germany Filed: Apr. 6, 1971 Appl. No.: 131,796

Foreign Application Priority Data Apr. 14, 1970 Germany 2017744 US. Cl 252/56 S, 252/59 Int. Cl C10m 1/28 Field of Search 252/56 S, 59

References Cited UNITED STATES PATENTS 9/1952 Morway et a1 252/56 S 2,746,925 5/1956 Garber et al 252/59 2,891,084 6/1959 Alm et a1 252/56 S 3,098,042 7/1963 Morway et'al... 252/59 3,271,311 9/1966 Morway et a1..... 252/59 3,329,613 7/1967 Fischer et a1. 252/59 Primary ExaminerDaniel E. Wyman Assistant ExaminerY. H. Smith Attorney, Agent, or FirmJohnston, Keil, Thompson & Shurtleff 57 ABSTRACT 4 Claims, N0 Drawings SYNTHETIC LUBRICANTS RESISTANT TO SHEAR AND COLD This invention relates to shear-resistant and coldresistant synthetic lubricants.

In industry there is an ever-increasing demand for lubricating oils showing good flow at low temperatures yet possessing adequate viscosity at higher temperanumber of reasons. If the amount of VI. improvers e.g. polyacrylates or polymethacrylates added is to remain within tolerable limits, the use or additional use of paraffin base oils is inevitable. Cooling of the oils causes the pour point to be reached as a result of crystallization of solid paraffins. Although the pour point may be lowered by the addition of pour point depressants, the viscosities in the range between the turbidity point and pour remain higher than anticipated for the liquid phase due to the precipitation of crystallizable paraffin components; distinct differences may be observed between the low-temperature viscosity calculated by extrapolation of viscosity measurements made at higher temperatures by the method described in German Standard Specification DIN 51563 and the lowtemperature viscosity as actually measured. This increased viscosity greatly restricts the range of application of these oils.

Moreover, such multi-grade oils containing V.I. improvers are not stable to the action of shearing forces encountered under operating conditions. The resulting decrease in viscosity and reduction of the viscosity index impairs the viscosity/temperature characteristic and the original multi-grade character of the oil is lost. Finally, the addition of VI. improvers modifies the stability of the oil, and such modification must be counteracted by increasing the addition of inhibitors and materials having a cleaning effect on the interior of the engine.

Lubricants based on dicarboxylates, for example non-substituted or alkyl-substituted adipates and sebacates, have been known in the art for a number of years. The combined use of ester oils and mineral oils for lubricating purpose has also been known for many years.

Furthermore, in special lubricating applications requiring pure lubricants based on hydrocarbons and free from foreign matter, it is known to use liquid polymers of butenes or isobutylene. However, these polymers are unduly volatile compared with mineral oils of the same viscosity and their flash point characteristic is unsatisfactory. The said polymer oils have a viscosity/temperature characteristic which is approximately the same as that of mineral oils.

We have now found that excellent shear-resistant and cold-resistant synthetic lubricants are obtained by mixing esters of branchedchain dicarboxylic acids of from 16 to 22 carbon atoms and aliphatic alcohols of less than 6 carbon atoms with polymers of butenes having a molecular weight of from 1,200 to 4,500, the ester portion being from 10 to 95% by weight and the polymer portion being from-90 to 5% by weight.

Esters which-may be used in the present invention are, in particular, esters of heptadecanodioic acid with propanol, n-butanol or isobutanol or mixtures of these butanols. Other suitable esters are those of alkylsubstituted adipic or sebacic acids of from 16 to 22 carbon atoms, for example decyladipic acid, dodecyladipic acid, octylsebacic acid, dibutylsebacic acid and dihexylsebacic acid with ethanol, propanol or butanol as the alcohol component. Polymers which may be used according to the invention in admixture with the said esters are those having a molecular weight of from 1,200 to 4,500 as measured by the Staudinger method. They are light to heavy oils having viscosity/temperature characteristics similar to those of minerallubricating oils. The polymers are prepared by known methods and may, if desired, be hydrogenated before blending with the esters.

Particularly suitable mixtures for use in the present invention are those of from 45 to by weight of ester with from 55 to 20% by weight of a polymer having a molecular weight of from 2,500 to 4,000 and mixtures of from 20 to 50% by weight of ester with from 80 to 50% by weight of a polymer having a molecular weight of from 1,200 to 3,000.

The previously known viscosity/temperatureimproved lubricants based on mineral lubricating oils or mixtures of mineral lubricating oils with ester oils have distinct disadvantages:

To achieve the usual multi-grade properties it is necessary to add a VI. improver. This gives these multigrade oils their wellknown susceptibility to shearing forces, which results in a reduction of viscosity in use.

The low-temperature viscosities are unfavorably influenced, i.e. raised, by the precipitation of paraffin from the mineral oil portion. The measured viscosities do not satisfy the viscosity/temperature relationship given in German Standard Specification DIN 51563. This restricts the range of utility of the oils at low temperatures.

The stability of esters is impaired when they are blended with a mineral base oil. This is shown in stability tests using the test strip apparatus by Wolf..For example, a di-n-butyl heptadecanodicarboxylate achieves the high relating of 8.5 when tested in this apparatus without any additive, whilst the rating achieved by a conventional rn'ineral base oil without any additive is 5.0. A mixture of the ester with the same base oil (with no further additive) in a ratio of 1:1 also achieves a value of 5.0. The better stability of the ester oil is lost when the latter is mixed with a mineral base oil.

However, by mixing dicarboxylates with polymers of butenes according to the present invention multi-grade oils are provided which are completely stable to shear and which satisfy the V/T relationship given in German Standard Specification DIN 51 563 down to very low temperatures, e.g. 40C. In addition, the mixtures of the invention show superior aging stability to comparable lubricants containing mineral oil.

EXAMPLE 1 Number of passes through Bosch nozzle 1 2 5 1 est at 378C 68.89 62.20 61.27 60.85 60.00 59.46 cSt at 98.9C 10.78 9.38 9.15 8.98 8.86 8.76 V.1. 136 130 128 126 126 125 Extrapolated according to according DlN 51562 to DlN 51563 Viscosity at 989C 10.13 cSt 37.8C 64.95 cSt- 17.8C 2220 about 2200 Viscosity index 134 SAE class l0W/30 Pour point 57C. Flash point 236C Noack test (250C) 12% Conradson carbon residue The 011 thus obtained has excellent cold viscosities. By comparison, the viscosities, as measured by German Standard DIN 51562, of comparable commercial oils based on a mineral oil are much higher at low temperatures and differ from the values obtained by extrapolat1on:

HQ iY n A1 11.19203 m ds? Q1 p pared by adding 4.8% of a V.1. improver and 5.2% of a detergent/inhibitor combination to a mineral lubricating oil. It has a viscosity index of 136.

The comparative oil B is also a 10W/30 multi-grade oil which canin tioivev riTn'iidditi on tothe 11mm lubricating oil, 23% of di-n-butyl heptadecanodicar-. boxylate as oil component. In this case the amount of V.I. improver added is 3% and that of the detergent/inhibitor combination is 6%. The viscosity index is 134.

The oil of the invention as described in this Example also possesses absolute stability to shear. Testing of the shear resistance by the method of forcing the oil A stability test using the test strip apparatus gave the 0 following results:

Rating 63% di-n-butyl heptadecanodicarboxylate} 8.5 37% poly(isobutylene) mol.wt. 3.000 63% di-n-butylheptadecanodicarboxylate 37% mineral lubricating oil Solvent 5.0 to 5.5

Neutral (2.5E/SOC) mineral lubricating oil Solvent 5.0

Neutral (2.5E/50C) The oil of the invention as described in Example 1 has the rating 8.5. This rating is excellent for an oil not containing any additives for improving the detergent/- dispersant characteristic. The rating of commerical HD oils of the test strip apparatus is between 8.0 and 10.0, whilst mineral base oils achieve ratings of approximately 5. 1f the esters are not mixed with poly(isobutylene) as proposed by the invention but with a conventional mineral base oil, the rating achieved is much the same as that of the mineral base oil alone.

EXAMPLE 2 50 parts of di-n-butyl heptadecanodicarboxylate are mixed with 50 parts of poly(isobutylene) having a molecular weight of 3,200. The mixture has the properties of a 20W/50 multi-grade oil having excellent cold viscosities and shear resistance:

shear test .the oil has the following values:

through a Bosch-Diesel injection nozzle at a pressure of Viscosity at 989C 111.05 cSt 200 atmospheres shows no reduction of the viscosity or 55 V I C R2 of the viscosity index: E class lbw/50 Number of passes through Bosch nozzle 0 1 2 5 1 20 cSt at 378C 64.95 65.30 64.32 64.57 65.43 64.91

cSt at 989C 10.13 10.11 10.11 10.16 10.13 10.10

The comparative oil A, tested under the same conditions, shows a distinct loss of viscosity and reduction of the viscosity index:

A comparable commercial 20W/50 oil prepared by mixing a mineral base oil with a V.1. improver and a detergent/inhibitor combination, has the following data:

Measured Extrapolated Viscosity at 989C 17.94 cSt 30C no longer measurable 25000 cSt V.l. 129 SAE class W/50 Pour point 40C In the shear test, the viscosity of the oil fell to the following values after 20 passes through the Bosch nozzle:

Viscosity at 989C l5.l4 cSt 378C 124.33 cSl V.l. 123 SAE class 20W/40 EXAMPLE 3 Measured Extrapolated Viscosity at 989C 17.80 cSt 37.8C l7l.0 l7l8C 12700 cSt 13200 cSt V.l. ll7 SAE class 80/90 These data remain unchanged after 20 passes throughaBosch nozzle. I

The oils produced by mixing esters and polylisobutylene) as proposed by the invention may be used as such for lubricating purpose; or conventional lubricant additives may be added, such as those for improving the detergent characteristic, the attrition characteristic, the resistance to oxidation and the pressure resistance, to extend the range of application of the oils. However, the addition of V.l. improvers is not necessary.

The lubricants of the invention may be advantageously used in a variety of lubricating applications.

For example they may be used as engine oils, gear oils,

hydraulic oils, ATF oils, shock-absorber oils, turbine oils and oils for lubricating aeroturbines.

We claim:

1. Shear-resistant and cold-resistant synthetic lubri cants consisting essentially of a mixture of. esters of branched-chain dicarboxylic acids of from 16 to 22 carbon atoms and aliphatic alcohols of less than 6 carbon atoms with homopolymers of butenes having a molecular weight of 2,500 to 4,000, said esters being 45 to by weight of said mixture and said homopolymers being 55 to 20% by weight of said mixture.

2. Shear-resistant and cold-resistant synthetic lubricants consisting essentially of a mixture of esters of branched-chain dicarboxylic acids of from 16 to 22 carbon atoms and aliphatic alcohols of less than 6 carbon atoms with homopolymers of butenes having a molecular weight of 1,200 to 3,000, said esters being 20 to 50% by weight said mixture and said homopolymers being 80 to 50% by weight of said mixture.

3. Lubricants as claimed in claim 2 wherein said ester component is the ester of heptadecanodioic acid with n-butanol, isobutanol or mixtures thereof.

4, Lubricants as claimed in claim 1 wherein said ester component is the ester of heptadecanodioic acid with n-butanol, isobutanol or mixtures thereof.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3,860,522

DATED Jan. 14, 1975 INV ENTOR(S) Diether Fischer, Paul Hornberger, Willy Wolf It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading, third line in the section of the Inventors, delete"Zlegelgaerten" AND substitute -Ziegelgaerten.

In the heading, fourth line in the section of the Inventors, delete "Mitlasch" and substitute -Mittasch-.

Column 6, line 29, delete "weight said mixture and substitute--weight of said mixture.

Signed and Stalled this fourth Day of May 1976 [SEAL] Arrest.

RUTH. C. MA.SON C. MARSHALL DANN 4! 11i?" (ummissimwr ()fPtlIL-HIS and Trademarks 

2. Shear-resistant and cold-resistant synthetic lubricants consisting essentially of a mixture of esters of branched-chain dicarboxylic acids of from 16 to 22 carbon atoms and aliphatic alcohols of less than 6 carbon atoms with homopolymers of butenes having a molecular weight of 1,200 to 3,000, said esters being 20 to 50% by weight said mixture and said homopolymers being 80 to 50% by weight of said mixture.
 3. Lubricants as claimed in claim 2 wherein said ester component is the ester of heptadecanodioic acid with n-butanol, isobutanol or mixtures thereof.
 4. LubricantS as claimed in claim 1 wherein said ester component is the ester of heptadecanodioic acid with n-butanol, isobutanol or mixtures thereof. 